|
这两天看BlueDavy写的一篇OSGi入门的文章《OSGi实战》,在道客巴巴有这篇文章的链接。
在这篇文章里面有这样一个例子:一个网站,有一个验证用户名和密码的页面(UserValidatorWebBundle)。验证的方式有三种:LDAP验证(LDAPValidatorBundle)﹑数据库验证(DBValidatorBundle)和配置文件验证(ConfigValidatorBundle)。在OSGi框架来讲,这分别是四个Bundle,UserValidatorWebBundle提供前端Web访问服务,执行时需要调用到三个验证Bundle中某一个提供的验证服务。三个验证Bundle在实际环境下可以通过启动其中一个﹑停止其它两个的方法实现动态的改变验证方式。
另外,还有一个UserValidatorBundle,这个Bundle实际上只包含了一个验证服务的接口类,在LDAPValidatorBundle﹑DBValidatorBundle和ConfigValidatorBundle三个Bundle之间提供验证服务的公共定义。
特别说明,我的开发环境是Eclipse JaveEE Indigo 3.7.2。
实现UserValidatorBundle
UserValidatorBundle提供验证服务的接口类Validator。由于它不要注册任何的服务和监听器,因此这里我们不需要为该Bundle提供Activator实现。它的作用就是将验证接口Validator通在MANIFEST.MF的Export-Package导出去,然后供其它具体实现验证服务的Bundle使用。
Bundle的详细开发过程可以参考《OSGi系列 - 用Eclipse开发Bundle》,这里只对关键地方进行说明。
UserValidatorBundle的目录结构,注意该Bundle没有Activator类:
Validator.java文件内容:
package org.riawork.demo.service.user;
public interface Validator {
public boolean validate(String username, String password) throws Exception;
}
打开MANIFEST.MF文件,在出现的元数据编辑页面中选择底部的Runtime标签页,然后点击Exported Packages旁边的Add...按钮,添加如下的内容:
这个操作实际上就是在MANIFEST.MF文件里面增加一条Export-Package项目:
Export-Package: org.riawork.demo.service.user
MANIFEST.MF文件完整的内容:
Manifest-Version: 1.0
Bundle-ManifestVersion: 2
Bundle-Name: UserValidatorBundle
Bundle-SymbolicName: UserValidatorBundle
Bundle-Version: 1.0.0
Import-Package: org.osgi.framework;version="1.3.0"
Bundle-RequiredExecutionEnvironment: JavaSE-1.6
Export-Package: org.riawork.demo.service.user
实现LDAPValidatorBundle
LDAPValidatorBundle提供LDAP验证方式。
LDAPValidatorBundle提供了一个LDAPValidator验证类,该类需要实现UserValidatorBundle里面的Valdiator接口,因此需要在MANIFEST.MF文件中通过Import-Package导入Validator接口所在的包org.riawork.demo.service.user。
LDAPValidatorBundle同时也提供了一个LDAPActivator类,用来管理Bundle的生命周期,在start()和stop()方法中实现LDAPValidator验证服务的注册和卸载。
作为演示用途,这里所有的验证方式都使用的是字符串硬编码的简单方式。
LDAPValidatorBundle的目录结构:
打开MANIFEST.MF文件,在出现的元数据编辑页面中选择底部的Dependencies标签页,然后点击Imported Packages旁边的Add...按钮,添加如下的内容:
这个操作实际上就是在MANIFEST.MF文件里面增加一条Import-Package项目:
Import-Package: org.osgi.framework;version="1.3.0",
org.riawork.demo.service.user
MANIFEST.MF文件完整的内容:
Manifest-Version: 1.0
Bundle-ManifestVersion: 2
Bundle-Name: LDAPValidatorBundle
Bundle-SymbolicName: LDAPValidatorBundle
Bundle-Version: 1.0.0
Bundle-Activator: org.riawork.demo.service.user.impl.LDAPActivator
Import-Package: org.osgi.framework;version="1.3.0",
org.riawork.demo.service.user
Bundle-RequiredExecutionEnvironment: JavaSE-1.6
LDAPValidator.java文件内容:
package org.riawork.demo.service.user.impl;
import org.riawork.demo.service.user.Validator;
public class LDAPValidator implements Validator {
public boolean validate(String username, String password) throws Exception {
System.out.println("LDAPValidator.validate()方法被调用");
if ("jerry".equals(username) && "jerry".equals(password)){
return true;
}
return false;
}
}
LDAPActivator.java文件内容:
package org.riawork.demo.service.user.impl;
import org.osgi.framework.BundleActivator;
import org.osgi.framework.BundleContext;
import org.osgi.framework.ServiceRegistration;
import org.riawork.demo.service.user.Validator;
public class LDAPActivator implements BundleActivator {
private ServiceRegistration serviceReg = null;
public void start(BundleContext bundleContext) throws Exception {
System.out.println("LDAPValidator服务被注册");
serviceReg = bundleContext.registerService(Validator.class.getName(), new LDAPValidator(), null);
}
public void stop(BundleContext bundleContext) throws Exception {
if(serviceReg != null)
serviceReg.unregister();
System.out.println("LDAPValidator服务被卸载");
}
}
实现DBValidatorBundle
DBValidatorBundle提供数据库验证方式,该Bundle的实现方式完全同LDAPValidatorBundle。
DBValidatorBundle的目录结构:
MANIFEST.MF文件内容:
Manifest-Version: 1.0
Bundle-ManifestVersion: 2
Bundle-Name: DBValidatorBundle
Bundle-SymbolicName: DBValidatorBundle
Bundle-Version: 1.0.0
Bundle-Activator: org.riawork.demo.service.user.impl.DBActivator
Import-Package: org.osgi.framework;version="1.3.0",
org.riawork.demo.service.user
Bundle-RequiredExecutionEnvironment: JavaSE-1.6
DBValidator.java文件内容:
package org.riawork.demo.service.user.impl;
import org.riawork.demo.service.user.Validator;
public class DBValidator implements Validator {
public boolean validate(String username, String password) throws Exception {
System.out.println("DBValidator.validate()方法被调用");
if ("jerry".equals(username) && "jerry".equals(password)){
return true;
}
return false;
}
}
DBActivator.java文件内容:
package org.riawork.demo.service.user.impl;
import org.osgi.framework.BundleActivator;
import org.osgi.framework.BundleContext;
import org.osgi.framework.ServiceRegistration;
import org.riawork.demo.service.user.Validator;
public class DBActivator implements BundleActivator {
private ServiceRegistration serviceReg = null;
public void start(BundleContext bundleContext) throws Exception {
System.out.println("DBValidator服务被注册");
serviceReg = bundleContext.registerService(Validator.class.getName(), new DBValidator(), null);
}
public void stop(BundleContext bundleContext) throws Exception {
if(serviceReg != null)
serviceReg.unregister();
System.out.println("DBValidator服务被卸载");
}
}
实现ConfigValidatorBundle
ConfigValidatorBundle提供配置人家验证方式,该Bundle的实现方式完全同LDAPValidatorBundle。
ConfigValidatorBundle的目录结构:
MANIFEST.MF文件内容:
Manifest-Version: 1.0
Bundle-ManifestVersion: 2
Bundle-Name: ConfigValidatorBundle
Bundle-SymbolicName: ConfigValidatorBundle
Bundle-Version: 1.0.0
Bundle-Activator: org.riawork.demo.service.user.impl.ConfigActivator
Import-Package: org.osgi.framework;version="1.3.0",
org.riawork.demo.service.user
Bundle-RequiredExecutionEnvironment: JavaSE-1.6
ConfigValidator.java文件内容:
package org.riawork.demo.service.user.impl;
import org.riawork.demo.service.user.Validator;
public class ConfigValidator implements Validator {
public boolean validate(String username, String password) throws Exception {
System.out.println("ConfigValidator.validate()方法被调用");
if ("jerry".equals(username) && "jerry".equals(password)){
return true;
}
return false;
}
}
ConfigActivator.java文件内容:
package org.riawork.demo.service.user.impl;
import org.osgi.framework.BundleActivator;
import org.osgi.framework.BundleContext;
import org.osgi.framework.ServiceRegistration;
import org.riawork.demo.service.user.Validator;
public class ConfigActivator implements BundleActivator {
private ServiceRegistration serviceReg = null;
public void start(BundleContext bundleContext) throws Exception {
System.out.println("ConfigValidator服务被注册");
serviceReg = bundleContext.registerService(Validator.class.getName(), new ConfigValidator(), null);
}
public void stop(BundleContext bundleContext) throws Exception {
if(serviceReg != null)
serviceReg.unregister();
System.out.println("ConfigValidator服务被卸载");
}
}
实现UserValidatorWebBundle
UserValidatorWebBundle提供使用者前端访问。该Bundle提供一个login.html页面,输入用户名和密码后,点击登录按钮,将数据提交到LoginServlet。LoginServlet检查,获取已经注册的Validator验证服务,调用validate()方法检查传过来的用户名和密码是否正确。
该Bundle使用到了Servlet API和HTTP服务,因此必需javax.servlet和org.eclipse.osgi.services两个额外的Bundle。
UserValidatorWebBundle的目录结构:
打开MANIFEST.MF文件,选择底部的Dependencies标签页,添加如下的内容:
这个操作实际上就是在MANIFEST.MF文件里面增加Import-Package项目和Require-Bundle项目:
Import-Package: org.osgi.framework;version="1.3.0",
org.riawork.demo.service.user
Require-Bundle: javax.servlet;bundle-version="2.5.0",
org.eclipse.osgi.services;bundle-version="3.3.0"
MANIFEST.MF文件完整的内容:
Manifest-Version: 1.0
Bundle-ManifestVersion: 2
Bundle-Name: UserValidatorWebBundle
Bundle-SymbolicName: UserValidatorWebBundle
Bundle-Version: 1.0.0
Bundle-Activator: org.riawork.demo.web.Activator
Import-Package: org.osgi.framework;version="1.3.0",
org.riawork.demo.service.user
Bundle-RequiredExecutionEnvironment: JavaSE-1.6
Require-Bundle: javax.servlet;bundle-version="2.5.0",
org.eclipse.osgi.services;bundle-version="3.3.0"
在src目录下新建page目录,然后在page目录下新增login.html文件。login.html文件内容:
<HTML>
<HEAD>
<TITLE>OSGI Opendoc Demo</TITLE>
<meta http-equiv="Content-Type" content="text/html;charset=utf-8" />
<script>
function login(){
if(document.frmLogin.username.value==""){
alert("必须输入用户名");
document.frmLogin.username.focus();
return;
}
if(document.frmLogin.userpass.value==""){
alert("必须输入密码");
document.frmLogin.userpass.focus();
return;
}
document.frmLogin.submit();
}
</script>
</HEAD>
<BODY>
<table style="width:45%;border:1px solid;height:100px">
<form name=frmLogin method="post" action="/demo/login">
<tr bgcolor="#C0C0C0">
<td colspan="2" align="center">用户登录模块示例</td>
</tr>
<tr>
<td width="30%">用户名</td>
<td><input type="text" name="username" size="30"></td>
</tr>
<tr>
<td>密 码</td>
<td><input type="password" name="userpass" size="33"></td>
</tr>
<tr bgcolor="#C0C0C0">
<td colspan="2" align="center">
<input type=button name=btnSubmit value="登录" onclick="login();">
</td>
</tr>
</form>
</table>
</BODY>
</HTML>
LoginServlet.java文件内容:
package org.riawork.demo.web;
import java.io.IOException;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.osgi.framework.BundleContext;
import org.osgi.framework.ServiceReference;
import org.riawork.demo.service.user.Validator;
public class LoginServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
private BundleContext context;
public LoginServlet(BundleContext context){
this.context=context;
}
/**
* Web Post Method
*/
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws IOException{
doGet(request, response);
}
/**
* Web GET Method
*/
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws IOException{
String username=request.getParameter("username");
String userpass=request.getParameter("userpass");
response.setContentType("text/html");
ServletOutputStream output=response.getOutputStream();
ServiceReference serviceRef=context.getServiceReference(Validator.class.getName());
Validator validator=(Validator) context.getService(serviceRef);
if(validator==null){
output.println("No usable validator service");
output.close();
return;
}
boolean result=false;
try {
result=validator.validate(username, userpass);
if(result)
output.println("Login success");
else
output.println("Login Fail,please check username and password");
output.close();
return;
}
catch (Exception e) {
output.println("Login error:");
output.println(e.toString());
return;
}
}
}
Activator.java文件内容:
package org.riawork.demo.web;
import javax.servlet.Servlet;
import org.osgi.framework.BundleActivator;
import org.osgi.framework.BundleContext;
import org.osgi.framework.ServiceEvent;
import org.osgi.framework.ServiceListener;
import org.osgi.framework.ServiceReference;
import org.osgi.service.http.HttpService;
import org.riawork.demo.web.LoginServlet;
public class Activator implements BundleActivator,ServiceListener{
private BundleContext bc;
private ServiceReference ref;
private Servlet servlet;
public void start(BundleContext context) throws Exception {
bc=context;
servlet=new LoginServlet(bc);
registerServlet();
context.addServiceListener(this, "(objectClass=" + HttpService.class.getName() + ")");
}
public void stop(BundleContext context) throws Exception {
try {
unregisterServlet();
} catch (Throwable t) {
t.printStackTrace();
}
servlet = null;
bc = null;
ref = null;
}
public void serviceChanged(ServiceEvent event) {
switch (event.getType()){
case ServiceEvent.REGISTERED:
registerServlet();
break;
case ServiceEvent.UNREGISTERING:
unregisterServlet();
break;
}
}
private void registerServlet() {
if (ref == null)
ref = bc.getServiceReference(HttpService.class.getName());
if (ref != null) {
try {
HttpService http = (HttpService) bc.getService(ref);
http.registerServlet("/demo/login", servlet, null, null);
http.registerResources("/demo/page","page",null);
System.out.println("已启动用户登录验证web模块,请通过/demo/page/login.htm访问");
}
catch (Exception e) {
e.printStackTrace();
}
}
}
private void unregisterServlet() {
if (ref != null) {
try {
HttpService http = (HttpService) bc.getService(ref);
http.unregister("/demo/login");
http.unregister("/demo/page");
System.out.println("已卸载用户登录验证web模块!");
}
catch(Exception e){
e.printStackTrace();
}
}
}
}
创建OSGi Run Configuration
选择菜单Run >> Run Configurations...,在弹出的Run Configurations对话框左边找到OSGi Framework,在该项目上点击鼠标右键选择New菜单项,画面如下:
下表的Bundle在Run Configurations对话框中必须被选中:
- UserValidatorBundle
- LDAPValidatorBundle
- DBValidatorBundle
- ConfigValidatorBundle
- UserValidatorWebBundle
- javax.servlet
- org.eclipse.osgi.services
- org.eclipse.equinox.http.servlet
- org.eclipse.equinox.http.jetty
- org.mortbay.jetty.server
- org.mortbay.jetty.util
配置完毕后,点击右下角的Run按钮,启动OSGi框架。如果一切正常,就会出现osgi>提示符,以及Bundle被启动时输出的提示信息:
从上图我们应该发现一个问题,实际上三个不同的验证方式都被启动了。
动态的切换验证方式
打开浏览器,输入http://localhost/demo/page/login.html,出现输入用户名和密码画面:
输入一个用户名和密码(正确的是jerry和jerry),点击登录按钮,浏览器网址转到了http://localhost/demo/login,这实际上就是我们注册的LoginServlet(参考UserValidatorWebBundle的Activator.java文件)。
请注意,这个时候我们查看OSGi控制台,有看到一条信息“ConfigValidator.validate()方法被调用”,说明当前使用的验证方式是配置文件验证。因为我们提供的三种验证服务都被启动了,换句话说,在OSGi框架中,Validator服务有三个提供者,在服务被调用时具体用的是哪一个提供者会由OSGi框架随机的决定。
停止Config和DB验证,只启动LDAP验证,然后再次提交http://localhost/demo/page/login.html,观察OSGi控制台,发现这次使用的是LDAP验证。
停止LDAP和Config验证,启动DB验证,观察OSGi控制台,是不是就是我们所期望的DB验证?
这篇文章实在是有点太长了,对于没耐心从头看到尾的朋友,下面提供了一个压缩文件下载链接,希望能帮助你省一点点时间。
http://files.cnblogs.com/eastson/osgi-user-valiator-code.rar |
|
|